Various thermal transfer recording systems are known in the art, and one of them is a recording system in which, using a thermal transfer film comprising a substrate film bearing a hot-melt ink layer containing a colorant, such as a pigment, and a vehicle, such as wax, or a sublimzable dye ink layer formed of a sublimable dye, a resin and the like, a colorant is transferred onto an image-receiving sheet or the like by heating means, such as a thermal head or a laser beam, to form an image.
In particular, a sublimation dye thermal transfer recording system using a thermal transfer film having a sublimable dye ink layer can express density gradation, creates a very sharp image, has excellent halftone color reproduction and gradation reproduction, and can form an image having a quality comparable to that formed by silver salt photography and, hence, is rapidly expanding its market to various applications.
These thermal transfer recording systems enable various images to be simply formed and, hence, have become utilized in prints wherein the number thereof may be relatively small, for example, in the preparation of identification (ID) cards and the like.
In the field of ID cards and the like, the security is particularly important. For this reason, the provision of a hologram image on an ID image formed using the thermal transfer film as described above has been proposed for the purpose of preventing alteration of ID cards and the like (Japanese Patent Laid-Open No. 159794/1991).
In an ID card or the like, however, the transfer of a hologram layer directly onto a transferred image of a sublimable dye ink by means of a thermal head or a hot stamper or the lamination of a hot-bondable laminate sheet including a hologram layer, that is, a hot-bondable hologram label (seal), onto the transferred image by applying heat and pressure using a hot plate or a hot roll does not pose any problem for some time. However, the resultant print with a hologram unfavorably causes bleeding in an image formed by sublimation dye transfer during use of the print for a long period of time, making it impossible to continue use of the print.
The cause of this unfavorable phenomenon has been considered attributable to the presence of a material, which is likely to cause bleeding of a sublimable dye, such as a resin having a low glass transition point or a plasticizer, incorporated, for the purpose of facilitating the transfer or heat bonding, into an adhesive layer in the hologram layer or the laminate including a hologram layer to be transferred or heat-bonded on the transferred image of a sublimable dye.
In view of the above, the present invention has been made, and an object of the present invention is to provide a print with a hologram, suitable as a print required to have a security property, such as ID cards, which is excellent in sharpness of a full-color image formed by the thermal transfer system, possesses excellent halftone color reproduction and gradation reproduction, has an optical diffraction structure, for preventing fabrication and alteration of the print, laminated onto the print to impart a security property to the print, and is free from the occurrence of bleeding or the like in the transferred image even after storage for a long period of time and excellent also in durability, and a process for producing the same.